Using high-energy, high-frequency, high-power characteristics of the laser, high-energy is instantly deposited in a small area, and the high-temperature burning oxide layer is also called laser cleaning.
Its physical principles can be summarized as follows:
a) The beam emitted by the laser is absorbed by the contaminated layer to be treated.
b) The absorption of large energy forms a rapidly expanding plasma, producing a shock wave.
c) Shock waves cause the contaminants to become fragments and are rejected.
d) The light pulse width must be short enough to prevent heat buildup from damaging the surface to be treated.
If the contaminated layer is thick, multiple pulses are required for cleaning. The number of pulses required to clean the surface depends on the degree of surface contamination.
Common treatment methods:
Metal surface descaling In addition to the emerging laser processing methods, there are several common treatment methods, which can be roughly divided into four categories:
1. manual descaling method
Use a scraper, a hammer, a steel brush, a grinding wheel, etc. to knock, shovel, grind, scrape, etc. to remove the rust.
2. mechanical rust removal method
Use portable electric grinding wheel, electric brush, wind brush, derusting gun, etc. to effectively remove rust and dirt by impact and friction. The most widely used methods are injection and shot blasting.
3. Chemical treatment
The acid solution reacts with the rust (oxide) on the surface of the metal to be cleaned, so that it dissolves in the acid solution, and the hydrogen generated by the action of the acid and the metal causes the scale to mechanically fall off.
4. ultrasonic treatment
Use high frequency vibration to shake off the loose rust.
The current laser cleaning methods can be classified into the following two categories depending on the characteristics of the substrate material, the accuracy of the substrate surface, the surface roughness, and the type of particulate contaminants.
1. Laser dry cleaning method. The laser directly illuminates the surface of the object, and after contaminating the particles or the surface absorbs energy, the particles are separated from the surface by thermal diffusion, photolysis, gasification, and the like.
2. Laser wet cleaning method. Spray some non-polluting liquid (mainly water, sometimes alcohol) on the surface of the material to be cleaned, and then irradiate it with laser. After the liquid medium absorbs the laser energy, it will explode and vaporize, and push the surrounding polluted particles away from the surface of the material. . In addition, a so-called laser duplex cleaning method has been proposed. The laser energy is absorbed by the substrate material, and then the condensed intermediate medium is heated by heat convection, and the intermediate medium is explosively vaporized. Under the promotion of high airflow, the particles are separated from the substrate surface together with the intermediate medium.